Titanium-base alloys



Patented Dec. 16, 1952 TITANIUM-BASE ALLOYS Loring R. Frazier, Swampscott, Mass., assignor to General Electric Company, a corporation of N ew York No Drawing. Application December 29, 1951,

Serial No. 264,230

. Claims.

. 1 The present invention relates to new and useful' titanium-base alloys. More particularly; it is concerned with and has as its principal object the provision of a new titanium-base alloy possessing optimum strength and ductility characteristics.

The invention is based on the discovery that a titanium-base alloy having good strength and ductility characteristics at both room and elevated temperatures, should contain small but effective amounts of oxygen, iron, copper, manganese and aluminum. It has been found that a very useful level of strength and ductility characteristics can be obtained in such an alloy Without the use of large additions of strategically important metals, such as chromium, which have been present in certain of the known titaniumbase alloys. The alloys of the present invention are in general characterized by a minimum 0.2% offset yield strength of about 120,000 -p. s. i., a minimum room temperature tensile strength 01 about 140,000 p. s. i., and a minimum elongation of 15%.

In general, the alloys of the present invention consist, by weight, of from 0.1 to 0.5% oxygen, 0.3 to 2% copper, 0.3 to 2% iron, 0.5 to 2% manganese, 0.5 to 2% aluminum, with the balance titanium except for incidental impurities including carbon which do not aggregate more than about 0.1%. Particularly useful alloys for structural purposes at room and elevated temperatures are those containing from about 0.1 to 0.4% oxygen, and from 1 to 2% manganese, in addition to the prescribed amounts of the re-- maining alloying ingredients. The best combination of yield strength, tensile strength and ductility has been obtained in alloys containing from about 0.1 to 0.3% oxygen, 1 to 1.5% iron, about 1% carbon, 1 to 1.5% manganese, and about 1% aluminum. Preferably the alloying ingredients other than the oxygen should comprise at least 3.5% by weight of the alloy and preferably should be less than about 5%. .Some nitrogen may unavoidably be present in the alloys due to the presence thereof in the titanium base metal from which the alloy is prepared.

While any suitable method may be employed in the manufacture of the alloys of this invention, consistently good results have been obtained by are melting a mixture of the ingredients comprising the alloy. When necessary to obtain the desired oxygen content, titanium oxide may be added. The following table includes compositions and properties of various alloys both within and Without the scope of the present invention.

27 if t hP 0 sets rengt erccnt Percent gg 0 Fe Cu Mn Al yield ,room elonreduction r strength tempergation inarea 0 ature 0.2 1 l l 1 119,560 140,750 24 45.3 3 1 1 1 1 146,020 157,850 49.4 .1 .3 2.0 .3 1.0 103,000 118,000 13 23 .2 .3 1.5 ..5 1.0 108,000 124,000 l1 l7 .3 .3 1.0 1.0 1.0 125,000 140,000 '20 43 .4 .3 .5 1.5 1.0 105,000 120,000 22 '45 .5 .3 .3 2.0 1.0 140,000 146,000 22 46 .1 .5 .3 .5 1.0 128,000 136,000 22 48 .2 .5 2.0 1.0 1.0 127, 000 137,000 12 20 .3 .5 1.5 1.5 1.0 106,000 118,000 16 34 .4 .5 1.0 2.0 1.0 127,000 138,000 20 46 10-. .5 .5 .5 .5 1.0 118,000 135,000 20 42 11.--. .1 1.0 .5 1.0 1.0 130,000 140,000 20 40 12.... .2 1.0 .3 1.5 1.0 127,000 138,000 17 49 13 .3 1.0 2.0 2.0 1.0 142,000 155,000 9 21 14... .4 1.0 1.5 .3 1.0 105,000 116,000 21 45 15 .5 1.0 1.0 .5 1.0 ,000 16 .1 1.5 1.0 1.5 1.0 137,000 147,000 18 36 17.-.. .2 1.5 .5 2.0 1.0 120,000 130,000 14 34 20 18 .3 1.5 .3 .3 1.0 100,000 118,000 22 48 The test results set forth in the above table were on test bars taken from alloys which had been forged and thereafter heat-treated at about 1300 F. for one hour, followed by air cooling. In general, the alloys are forged at temperatures of from 1300 F. to about 1650 F., within which temperature range the alloy is soft and ductile enough for most forging operations. The use of more elevated temperatures in the presence of an oxidizing atmosphere may result in substantial diffusion of oxygen into the surface, with a detectible increase in hardness of the surface. The alloys can also be hot-rolled within the same temperature range and exhibit the usual machinability characteristics of other known titaniumbase alloys.

The optimum tensile strength and ductility characteristics exhibited by the alloys of the present invention make them particularly suitable as wheel and bucket or blade materials for use in the intermediate stages in gas turbine compressors and the like. In such applications, advantage can be taken of their marked reduction in weight as compared with comparable steel parts.

If desired, the formed parts can be surface hardened by diffusion of elements, such as oxygen or nitrogen into the surface, thereby altering the composition and properties of the surface layers.

Alloy D9 is representative of the alloys of the present invention insofar as their properties are concerned. This alloy, which has a room temperature tensile strength in excess of 140,000 p. s. i. exhibits a tensile strength of about 90,000 p. s. i. at 400 F., and 61,000 p. s. i. at 800 F. Its 1000-hour stress rupture value at 400 F. is 95,000 p. s. i., and at 800 F. is 21,000 p. s. i. In the forged and annealed state, the alloys of the present invention ordinarily have a Rockwell-C hardness of at least 30, and usually from 33 to about 38. Maximum hardness can'ordinarily be obtained by air cooling the alloy following a heat treatment at a temperature in the neighborhood of 1400 F. to 1800 F. for about one hour. Ordinarily, the hardness values for these alloys will not change or materially vary through exposure to elevated temperature up to about 900 F.

The presence of all of the enumerated elements within the designated ranges appears to be essential to obtain the optimum strength and ductility characteristics, while the iron and aluminum contents of the alloy appear to be the more critical insofar as the tensile properties 'of the alloy are concerned than the copper and manganese, test results on alloys containing only the oxygen, iron and aluminum in addition to titanium have indicated that desired elongation 4 or ductility characteristics cannot be obtained without the presence of efiective quantities of copper and manganese.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A titanium-base alloy consisting essentially of from 0.1 to 0.5% by weight oxygen, 0.3 to 2% copper, 0.3 to 2% iron, 0.5 to 2% manganese, 0.5 to 2% aluminum, balance substantially all titanium.

2. A titanium-base alloy consisting essentially of from 0.1 to 0.3% oxygen, 1 to 1.5% iron, 1% copper, 1 to 1.5% manganese, about 1% aluminum, balance substantially all titanium.

3. A titanium-base alloy consisting essentially of from 0.2 to 0.3% oxygen, 0.5 to 1% copper, about 1.5% iron, 1 to 2% manganese, about 1% aluminum, balance titanium.

4. A titanium-base alloy consisting essentially of 0.3% oxygen and 1% by weight each of iron, copper, manganese and aluminum, balance titanium.

5. A titanium-base alloy consisting essentially of about 0.1% oxygen, 1.5% iron, 1% copper, 1.5% manganese, and 1% aluminum, balance titanium.

LORING R. FRAZIER.

No references cited. 

1. A TITANIUM-BASE ALLOY CONSISTING ESSENTIALLY OF FROM 0.1 TO 0.5% BY WEIGHT OXYGEN, 0.3 TO 2% COPPER, 0.3 TO 2% IRON, 0.5 TO 2% MANGANESE, 0.5 TO 2% ALUMINUM, BALANCE SUBSTANTIALLY ALL TITANIUM. 